Watts to Amps Chart
Every common wattage at 120 V single phase, unity power factor — the household case. At 240 V halve every figure; on three phase divide by 1.732 as well. The breaker column is the continuous rating the load needs, not the current it draws.
Source data and formula checked · How we check
Watts to Amps Chart reads amps straight off watts or amps, for 30 values from 50 to 5000. Every row is computed from the same formula the calculator uses, not measured or copied from another table, so a value between two rows can be worked out the same way. The formula is the one published by IEEE Std 141.
| Watts or amps | Amps | Continuous load at 80% of a breaker |
|---|---|---|
| 50 | 0.42 A | 0.52 A |
| 100 | 0.83 A | 1.04 A |
| 150 | 1.25 A | 1.56 A |
| 200 | 1.67 A | 2.08 A |
| 250 | 2.08 A | 2.6 A |
| 300 | 2.50 A | 3.13 A |
| 400 | 3.33 A | 4.17 A |
| 500 | 4.17 A | 5.21 A |
| 600 | 5.00 A | 6.25 A |
| 700 | 5.83 A | 7.29 A |
| 750 | 6.25 A | 7.81 A |
| 800 | 6.67 A | 8.33 A |
| 900 | 7.50 A | 9.38 A |
| 1000 | 8.33 A | 10.42 A |
| 1100 | 9.17 A | 11.46 A |
| 1200 | 10.00 A | 12.5 A |
| 1300 | 10.83 A | 13.54 A |
| 1400 | 11.67 A | 14.58 A |
| 1500 | 12.50 A | 15.63 A |
| 1600 | 13.33 A | 16.67 A |
| 1800 | 15.00 A | 18.75 A |
| 2000 | 16.67 A | 20.83 A |
| 2200 | 18.33 A | 22.92 A |
| 2400 | 20.00 A | 25 A |
| 2500 | 20.83 A | 26.04 A |
| 3000 | 25.00 A | 31.25 A |
| 3500 | 29.17 A | 36.46 A |
| 4000 | 33.33 A | 41.67 A |
| 4500 | 37.50 A | 46.88 A |
| 5000 | 41.67 A | 52.08 A |
Questions people actually ask
- How do I read the Watts to Amps Chart?
- Find your watts or amps in the first column and read across. At 50 the amps is 0.42 A; at 5000 it is 41.67 A. The table runs from 50 to 5000 in 30 rows.
- How much does the amps change per row?
- By 0.42 A for every 50 of watts or amps, and by the same amount everywhere in the table — the relationship is a straight line, so halfway between two rows is halfway between their two answers. That is what makes reading between the rows safe here.
- What if my watts or amps is outside the table?
- The chart covers 50 to 5000, which is the range people actually look up. Anything above or below goes into the calculator, which takes any figure and shows each step of the working rather than only the result. Open the watts to amps.
- Where do these numbers come from?
- Every row is computed at build time from the formula published by IEEE Std 141, by the same code behind the calculator — not transcribed from another table, which is how a rounding error in one chart ends up in twenty.
Need a different number?
The chart covers the common values. For anything between the rows, the watts to amps takes any figure and shows the working.
Source: IEEE Std 141 — the √3 factor in three-phase power, NFPA 70 (NEC) 210.19(A)(1) — branch-circuit conductors sized at 125% of continuous load, NIST SP 811 — units for electrical quantities